The invention relates to a motorized anti-plaque toothbrush comprising a handle at one end of which is a cleaning/massaging head, in particular a brushing head, which rotates about an axis which is approximately perpendicular to the longitudinal axis of the handle and is turned with a continuous one-way rotary motion or with a reciprocating rotary motion by a motor, preferably an electric motor, housed in the handle.
The object of the invention is to provide a toothbrush of the type described above that will provide a more effective cleaning action and plaque-removal action, while at the same time, guaranteeing excellent treatment of the gingivae from the point of view of massaging and cleaning of the gingivae.
A further object is to improve the construction of a toothbrush of the type described at the outset in such a way that the drive parts and transmission parts, in particular, are easier to produce and assemble so that manufacturing costs are lower and the toothbrush is longer-lasting.
The invention achieves these objects in the form of a toothbrush of the type described at the outset, in which the cleaning/massaging head is composed of at least two separate cleaning/massaging tool parts that are supported coaxially with respect to each other in such a way that they can rotate relative to each other, being turned in mutually opposite directions in the case of continuous one-way rotation and in phase opposition to each other in the case of reciprocating rotation.
The rotary drive means and the cleaning/massaging tools may be of any type.
In the case of a brushing head, this head is composed of at least one tubular outer brush and at least one central inner brush that is coaxial with and rotates relative to the tubular outer brush, the bristles of both brushes lying generally parallel to the axis of rotation or of oscillation.
The free ends of the bristles of the tubular outer brush and central inner brush may terminate on the same flat or curved surface or they may be of different lengths from each other.
The two contrarotating parts of the brushing head give enhanced cleaning action and plaque-removing action. The advantageous gingivae messaging action is also improved.
According to a further characteristic of the invention, the means for turning the two coaxial brushes in a reciprocating manner in phase opposition to each other comprise:
a drive shaft that rotates continuously in one direction about its axis, which is perpendicular to the axis of rotation of the brushes; and
transmission means that transmit the rotary motion to the brushes and consist of a transmission spindle coupled in rotation to the drive shaft and dynamically engaged with both brush parts, being shaped in such a way that the two brush parts oscillate about their common axis of rotation between two extreme angular positions in phase opposition to each other.
The transmission spindle is made in the form of a shaft with bends.
In a particularly advantageous embodiment of the invention, the transmission spindle comprises an eccentric V-shaped segment oriented transversely to the axis of rotation of the drive shaft with its vertex more or less in the axis of rotation of the two coaxial brushes, while the tubular outer brush and the inner brush are provided with cylindrical bristle-carrying bases supported rotatably about their axis one inside the other, said bristle-carrying bases each being provided on diametrically opposite sides with an axial slot in which there respectively engages one of the inclined arms of the eccentric V segment, while on the same side as the slot of one of the bristle-carrying bases, the other bristle-carrying base comprises a through hole for the transmission spindle of a size that will prevent interference between the corresponding bristle-carrying base and the arm of the V segment engaged in the slot of the other bristle-carrying base.
The amplitude of the oscillation of the reciprocating rotary motion of the two coaxial brushes making up the brushing head may be varied and made different for each brush by varying the inclination to the longitudinal axis of the drive shaft of the two inclined arms of the V-spindle.
The arms of the V segment of the transmission spindle may lie in the same plane parallel to the axis of rotation of the drive shaft. In this case the movements of the two brushes are in perfect phase opposition. The relationship between the phases of the oscillatory motions of the two brushes can be varied by giving one of the arms of the V segment of the transmission spindle a further inclination transversely to the plane containing the other arm.
The transmission for driving the two brushes of the brushing head in a reciprocating manner and in phase opposition is extremely simple and is easy to manufacture, and the work required is not of high precision. It ensures the least possible disturbance to operation in the event of wear and means that the construction of the brush involves a very few inexpensive parts that can be assembled easily and quickly.
By means of obvious and appropriate modifications, the transmission according to the invention can also be used to oscillate a brushing head having just one brush, by limiting the construction of the transmission spindle to a single inclined arm.
Similarly, if the brushing head is composed of more than two contrarotating parts, it is possible, by means of obvious modifications, to use the transmission spindle to drive all said parts, by giving it additional inclined segments, each being engaged in a slot in the corresponding part.
The invention also relates to other characteristics which further improve the toothbrush described above and these are covered by the dependent claims.